The present invention relates generally to an interior illumination device and specifically to an interior illumination device that is fixed on a vehicle ceiling.
A map lamp is used for viewing a map in a dark interior compartment. The map lamp illuminates an area around a passenger.
Since a map lamp is used when it is dark, it is difficult to recognize where the map lamp is. Even though some light come into the interior compartment from outside, the light does not reach the map lamp easily because the map lamp is located on the vehicle ceiling. Thus, it is difficult to find the position of the map lamp. Therefore, a prior art map lamp includes a switch that includes a light source. The switch is indicated by the light source in the dark compartment. However, it is difficult to place a light source specialized for indicating a switch in the limited space. If the map lamp and the light source are housed in the limited space, installation is complex and relatively expensive.